iommu/amd: Wait for completion of IOTLB flush in attach_device

iommu/amd: Wait for completion of IOTLB flush in attach_device

BugLink: https://bugs.launchpad.net/bugs/1863019
[ Upstream commit 0b15e02f0cc4fb34a9160de7ba6db3a4013dc1b7 ]

To make sure the domain tlb flush completes before the
function returns, explicitly wait for its completion.

Signed-off-by: Filippo Sironi <sironi@amazon.de>
Fixes: 42a49f965a8d ("amd-iommu: flush domain tlb when attaching a new device")
[joro: Added commit message and fixes tag]
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>